1. Field of the Invention
The present invention relates to a cassette loader for a video recorder/reproducer and, more particularly, to a loading mechanism for reliably delivering a standard video cassette onto a pair of reel drive hubs of a video recorder/reproducer, insuring proper seating of the reels on the hubs, and preventing jamming of the video tape.
2. Description of the Prior Art
Video recoding tape is commonly supplied in a standard type of casette to eliminate the problems associated with open reels and the threading of the tape into a video recorder/reproducer. A variety of video recorder/reproducers have been developed for receiving standard video cassettes.
When using a standard video cassette with a video recorder/reproducer, the first problem becomes that of mating and demating the reels within the cassette to the reel drive system of the recorder/reproducer. For this purpose, a number of different systems have been developed for receiving the video cassette and lowering it onto the reel drive hubs which engage the reels for driving the tape in opposite directions.
The cassette loaders for video recorder/reproducers that have been developed heretofore have been intended for use with video recorder/reproducers designed for recording and playing back standard television type signals. In such systems, the tape travels at low speed, typically 3 3/4 inches per second during play back and 45 inches per second during rewind. Accuracy and reliability of operation have been relatively unimportant considerations.
On the other hand, the present cassette loader is designed for a video recorder/reproducer intended for use in a document acquisition and retrieval system. This environment places a number of constraints on the video tape and cassette which cannot be achieved with conventional cassette loaders. For example, the present cassette loader is intended for use in a system where tape travels in two directions, during a search mode, at speeds in excess of 400 inches per second. It is obvious that when tape is run at such speeds, it cannot rub, bump, or touch anything within the cassette or the tape may be irreversibly damaged and the data thereon lost. Steps must also be taken to insure that the cassette reels will be accurately seated on the reel drive hubs since the reel drive will typically be part of a servo system.
Another problem results from the fact that standard video cassettes are made by a number of different manufacturers and slight variations in tolerances and dimensions of the cassettes result. Furthermore, the video cassettes are typically made of plastic and warp in use. If a warped or deviated cassette is placed in a recorder/reproducer, the anomaly may cause jamming of the video tape during the high speed search mode.
If a cassette loader and a video recorder/reproducer are to be usable in a document acquisition and retrieval system, the video cassettes must be front loadable into the system in a simple, foolproof manner by a relatively untrained operator. This too has been a problem with cassette loaders designed heretofore. Still further, because of the environment, the recorder/reproducer may be positioned at any angle, not necessarily horizontal, requiring the video cassette to be inserted either horizontally or vertically or in any other angular orientation. Accordingly, it is desirable that the cassette loader not be subject to the influences of gravity, but be able to operate in any position. A cassette loader meeting the above requirements has been unavailable heretofore.